Apparatus for operating the blow-off valves of centrifugal compressors or pumps.



v H. GUYER APPARATUS FOR OPERATING THE .BLOW-OFF VALVES 0F CENTRIFUGALCOMPRESSORS 0R PUMPS- APPLICATION FILED JULY 8.191s.

1,241,372. A PatentedSept. 25, 1917.

2 SHEETS-SHEET I l -L. M E1 Y .9 5 Y 1 l l- I l l .l l 8 4 a E I 1 i 2 3'1 6 L liwenfifi' Hans Guyer.

A ll'orn 24y.

H. GUYER; APPARATUS ron OPERATING'THE BLOW-OFF VALVES or CENTRIFUGALCOMPRESSORS 0R PUMPS.

Patented Sept. 25, 1917.

2 SHEETS-SHEET 2.

APPLICATION FILED JULY 8. I913- HANS GUYER, OF ZURICH, SWITZERLAND,ASSIGNOR TO AKTIENGESELLSCHAFT DER MASCHINENFABRIKEN ESGHER, WYSS & 00.,OF ZURICH, SWITZERLAND.

APPARATUS FOR OPERATING THE BLOW-OFF VALVES OF CENTBIFUGAL COMPRESSOBSOR PUMPS.

To all whom it may concern:

Be it known that I, HANS GUYER, a c1t1- zen of the Swiss Republic,residing at No. 19 Hardturmstrasse, in Zurich, Switzerland, haveinvented certain new and useful Improvements in Apparatus for Operatingthe Blow-Off Valves of Centrifu al Compressors or Pumps, of which theollowing is a specification.

The present invention relates to a process, and to an apparatus forcarrying into effect said process, for the operation of a blowoff orreturn valve for centrifugal compressors and pumps. 7

In the accompanying drawings,

Figure 1 is a diagram illustrating the processrand hereinafter fullydescribed.

Figs. .2, 3 and 4 illustrate three forms of apparatus by which theprocess is carried into eflect, and which are hereinafter fullydescribed. y

It is well known that with a certain speed of rotation in a deliveringmachine of this kind, stability only exists when the increase inpressure does not rise above a certain figure and the quantity to bedelivered'does not sink below a certain figure. If, in a diagram withright-angled coordinates, in whichthe quantity of fluid flowing throughthe compressor is represented ,as abscissa and the pressure increase asordinate, and these limit values for the stability are plotted fordifferent speeds of rotation, these'li mit values will lie on a certaincurve which may be termed the stability limit curve. Fig. 1 shows adiagram of this kind. In the direction of the axis O-X the quantity Q,delivered in the time unit is plotted, and in the direction of the axisO? the. appertaining pressure increase 7:. is plotted. For.

a certain speed of rotation n, the curve A B is the graphic illustrationfor the mutual dependence of the quantity Q of fluid flowing through thecompressor upon the pressure increase It and vice versa. Should thepressure rise from the value A A to the value B,'-B,, then the quantitydelivered sinks dually from the commencing value 0- to the value OB Ifnow the delivery pressure rises above the value B B then, in accordancewith ex erience, a state of unstable equilibrium will e established. Inother words the centrifugal compressor or pump begins to' pump.

Specification of letters latent.

Patented Sept. 25, 1917.

Application filed July 8, 1913. Serial No. 777,904.

Therefore for the speed of rotation n the point B is the boundary pointbetween the stable and the unstable condition of the quantity of fluidflowing through the compressor. For other speeds of rotation n, and n, asimilar curve A B or A,,B may be plotted within the range ofstability.The points B B and B =1ie on a-curvea.b, that is to say the stabilitylimit curve. The object of the present invention is; to automaticallyopen a blow-ofi or return valve or a similar member such as a slide flapor the like connected to the compressor, as soon as the conditions ofdelivery return out of the range of stability and cross the curve ab.Should a point, for instance C, representing the momentary delivery forany.

speed of rotation, lie to the right of the limit curve a-b in Fig. 1,which implies perfect stability of the delivery, then the blow-off orreturn member remainsclosed. Should the delivery quantity sink, or thepressure rise, or should both occur simultaneously, whereby thecharacteristic point C in the diagram is moved to the left or upward orin an intermediate direction, then according to the present invention,the blow-ofi valve should open when the point C goes beyond the limitcurve wb. Of'course the opening will not coincide absolutely or exactlywith thecurve wb; it is suflicient if the opening occurs at a conditionwhose graph lies in the neighborhood of'this curve. From the previousintroduction it is evident that the devices causing the opening must bede pendent both upon the delivery quantity Q and also upon the pressureincrease it in the delivering machine. It has hitherto been known thatfor a certain speed of rotation a critical point with reference to thepumping occurs. It was however not known that in general these pointslie on a curve known piping, and through the pipe 3 with a low pressurestage or the suction piping or the atmosphere. Should pressure rise yrthe quantity of the substance for instance air to be delivered, fall insuch a manner that the point illustrating this momentary delivery in thepressure volume diagram Fig. 1 falls to the left or over the curve 0-!)then the blow-ofi valve 1 in Fig. 2 should be opened. For this purposethe valve 1 is brought into communication with two auxiliary powermachines 4 and 5. Of these machines the first isconnected with a Venturimeter 7 which is built in the suction piping 6 of the compressor, inwhich meter during normal delivery there exists a certain vacuum withrelation to the outer air. This vacuum operates on the lower side of apiston of the auxiliary machine 4 while the same piston is loaded aboveby the atmosphere. In the same way the piston of the auxiliary powermachine 5 is loaded above by the atmosphere and below by the pressure-ofthe substance to be delivered on emerging from the compressor. For thispurpose the spacebelow the piston of the auxiliary machine 5 isconnected by means of the pipe 9 with the high pressurespace of thecompressor. The diameter of the cylinders 4 and 5 can be just sodetermined that the pressuresacting on their pistons durin normalworking will hold the valve 1 close Should the pressure in thecompressor rise abovea certain limit, the piston 5 is raised; and shouldthe delivery quantity fall and with it the'vacuum in the Venturi meter7, that is to say, if the absolute pressure under the piston of thepower machine 4 rise above 'a certain limit, .then the piston in thecylinder 4 is raised. Both alterations of the conditions cause the valve1 to rise "and consequently an outflowing or overflowing of the deliverysubstance out of the pressure space toward a place of lower| pressure.During this operation caused by one. piston the other piston issimply-dragged along. An oppositely directed motion occurs when thepressure in the condenser and therefore simultaneously the pressureunder the piston 5 drops, or when the..delivery quantity rises andtherefore the absolute pressure under the piston 4 drops. Should thepressure and the quantity .offluid flowin through the compressor rise orfall simu taneously, then their eflects on the two power machines 4 and5 can neutralize each other. so that the valve 1 does not move. It maybe imagined that the pressure and the quantity of fluid flowing throughthe compressor could rise together 1n such a manner that the pointillustrating their momentary condition moves along the curve ab ofFig. 1. As long as the 'point remains to the right of this curve, noblowing-01f will occur, but

this only takes place as soon as: it has reached or crossed the curvea-b after having moved to the left or upward.

According to Fig. 3 wherein the air discharged at the blow-ofl' valve isreturned by pipe 3 to the inlet end of the compressor, the two auxiliarypower machines 4 and 5 operate on a controlling valve 10 which al lowsof the passage of the auxiliary pressure fluid entering through the pipe11 passing either above or below the piston of a third auxiliary powermachine 12, which on controlling valve 10 of the third auxiliary powermachine 12.

The piston positions of the auxiliary machines 4 and 5 shown in Fig. 4should correspond to the conditions B on the curve ab in Fig. 1 with thespeed of rotation 0%,. Should the delivery quantity flowing through thesuction pipe 6 and the Venturi meter 7 rise, and therewith the absolutepressure under the piston 4 drop, then the outer atmosphere has thetendency to move this piston and thus the right hand end 15 of thedouble lever 13 downward against the action of the spring 14, sothatfthe double lever 13 rotates momentarily about its left hand end 16in a clockwise direction. Thereby sinks the controlling valve 10 whichallows the pressure liquid to flow over the piston of a third auxiliarypower machine chine 12 whereby said piston premes the outflow valve 1still tighter onto its seating than sure drops below the momentaryamount- B,B The piston 5 in Fig. 4 thereby sinks under the influence ofthe loading spring 17 and rotates the lever 13 about the momentarilyfixed point 15 in an anti-clockwise direction, lowers the controllingvalve 10 and allows pressure oil to enterjover the piston 12. Only whenthe piston4 alone, or the piston 5 alone are sufficiently raised, whichoccurs in consequence of a reduced delivery quantity or increasedpressure ri'se, is the ,controlling valve 10 again brought back into itsmiddle position. This 'position always corresponds to a point in thecurve ab in Diagram 1. Should the dc livery quantity sink further or thepressure rise further, then the controlling valve 10 is raised out ofits middle position and allows pressure liquid to enter under the piston12 whereby this is raised and the blow-ofl valve 1 is opened. Thecontrolling valve 10 can, however, remain in its middle position and theblow-ofl' valve 1 can remain closed, when the piston 4, in consequenceof an increase in delivery quantity, sinks, but the piston 5, inconsequence of simultaneous increase of pressure in the condenser,sufliciently rises. The lever 13 rotates hereby in a clockwise directionabout its center pivot 18 which, however, does not move vertically. Analteration of this kind of the delivery corresponds in the diagram Fig.1 to a sliding of the characteristic point C along the curve a,-b fromthe point B toward the point B,.

Of course other forms of construction maybe employed and return guiderods may be built in, in a known manner without altering the nature ofthe present invention.

What I claim is:

1. In a centrifugal compressor or pump, the combination with a blowofl'.valve, of controlling mechanism for said Valve, means for placing saidmechanism under the influence .of the delivery pressure and means forplacing -said mechanism under the influence of the quantity of fluidflowing through the compressor, so that the blow-ofi' valve willbeopened by said controlling mechanism at all speeds whenever the pointindicating the momentary delivery in the quantity pressure diagram fallson that side of the stability limiting curve where pumping or surgingoccurs.

2. In a centrifugal compressor or pump, the combination with a blow-01fvalve, of controlling mechanism for said valve comprising means movableunder the influence of the delivery pressure, means movable under theinfluence of the quantity of fluid flowing through the compressor, andmeans for transmitting the movements of said means to said valve, sothat the valve will be opened by said controlling mechanism at allspeeds whenever the point indicating the momentary delivery in thequantity pressure diagram falls on that side of the stability limitingcurve where pumping or surging occurs.

3. In a centrifugal compressor or pump, the combination with a' blow-offvalve, of controlling mechanism for said valve comprising power meansfor adjusting said valve, means movable under the influence of thedelivery pressure, means movable under the influence of the quantity offluid flowing through the compressor, and means for transmitting themovements of said means to said power means, so that the valve will beopened by said controlling mechanism at all speeds whenever the pointindicating the momentary delivery in the quantity pressure diagram fallson that side of the stability limiting curve where pumping or surgingoccurs.

4. In a centrifugal compressor or pump, the combination with a blow-oflvalve, of a power piston, means for placing said power piston under theinfluence of the delivery pressure, a second power piston, means forplacing said second power piston under the influence of the quantity 'offluid flowing through the compressor or pump, and mechanism fortransmitting the movements of both said power pistons to act upon saidvalve whereby the valve is adjusted so as to prevent pumping.

' 5. In a centrifu al compressor or pump, the combination with ablow-01f. valve of a power piston, means for placing said power pistonunder the influence of the delivery pressure, a second powerpiston,means for placing said second power piston under the influence of thequantity of fluid flowing through the compressor an auxiliary powermachine for adjusting said blow-01f valve, an auxiliary pressure fluidcontrolling valve for operating said auxiliary power machine, and meansfor causing the movements of both said power'pistons to act upon saidcontrolling valve.

6. In a centrifugal compressor or pump, the combination with a blow-ofivalve, of a power piston, means for placing said power piston under theinfluence of the delivery pressure, avsecond power'piston, means forplacing .said second power piston under the influence of the quantityof' fluid flowing through the compressor or pump, an auxiliary powermachine connected with the blow-ofl' valve and means for controllingsaid auxiliary power machine from the two power pistons, whereby theblow-ofl' valve is opened at all speeds whenever the point indicatingthe momentary delivery in the quantity-pressure diagram falls on thatside of the stability limit curve'where pumping or surging occurs.

7. In a centrifugal compressor or pump, the combination with-ablow-.ofl' valve, of a power piston, means for placing said power pistonunder the influence of the delivery pressure, a second power piston,means for placing said second power piston under the influence of thequantity of fluid flowing through the compressor or pump, an aum'liarypressure fluid power machine connected with the blow-ofl' valve andmeans for controlling-said auxiliary power machine from the two powerpistons, whereby the blowofl' valve is opened at all speeds whenever thepoint indicating the momentary delivery in the quantity-pressure diagramfalls on that side of the stability limit curve where pumping or surgingoccurs.

8. In aeentrifugal compressor or pump, the combination with a blow-offvalve, of a power piston, means for placing said power piston under theinfluence of the delivery pressure, a second power piston, means forplacing said second power piston under the influence of .the quantity offluid flowing through the compressor or pump, an auxiliary pressurefluid power machine connected with the blow-ofi' valve, a controllingvalve for said auxiliary power machine and means for transmitting themovement of both said power pistons to the controlling valve, wherebythe blow-01f valve is opened at all speeds whenever the point indicatingthe momentary delivery in the quantity-pressure diagram falls on thatside of the sta bility limit curve where pumping or surging occurs.

9. In a centrifugal compressor or pump, the combination with a blow-ofivalve, of a power piston, means for placing said power piston under theinfluence of the delivery pressure, a second power piston, means forplacing saidsecond power piston under the influence of the quantity offluid flowing through the compressor or pump, an auxiliary pressurefluid power machine connected with the blow-off valve, a controllingvalve for said auxiliary power machine and a double lever fortransmitting the movements of both said power pistons to the controllingvalve, whereby the blow-oil valve is opened at all speeds whenever thepoint indicating the momentary delivery in the quantitypressure diagramfalls on that side. of the I stability limit curve where pumping orsurging occurs.

10. In a centrifugal compressor, an intake and a discharge line, ademand measuring device, a blow as valve in said discharge line, meansoperated from said demand measuring device for opening said blow offvalve at a determined minimum volume and means to vary said determinedminimum in accordance with the pressure in said dis.- charge line.

11. In a-centrifugal compressor having a discharge line, a passageconnected with said compressor through which the demanded volume offluid-passes; a moving element connected with said passage and adaptedto move in accordance with the flow there through, a blow ofl' valve insaid discharge line operatively connected with said moving element, andadapted to be opened thereby at a minimum volume of flow through saidpassage, and a second moving element adapted to be moved in accordancewith the pressure, in said discharge line, said second element alsohaving operative connection with said blow oil valve to modify theaction of said first moving element.

12. In a centrifugal compressor, an inlet and discharge line for saidcompressor, a demand measuring device in the inlet line of saidcompressor, a blow off valve'in the discharge line of said compressorand a conduit for leading the blow off air back to the inlet of said,compressor.

In testimony whereof I affix my signature in presence of two witnesses.

HANS GUYER.

Witnesses:

CARL Gunman,

ARNOLD LEHNER.-

